Slack should be handled by effective management. Having clearly defined deadlines and checkups on progress prevents people from wasting time in a detrimental way. Instilling fear in your devs by threatening to expose them when they goof off is not how you should treat professionals.

So I goof off. Perhaps I don't even work for an entire day. Am I meeting the schedule laid out for me? Am I producing as much as expected while being happy and carefully managing my output?

Forcing engineers to work nonstop is a good way to create buggy software.

There needs to be a shift in the industry to respecting what people get done rather than how many hours they spent working on it.